Image compression encoder and image compression encoding method

ABSTRACT

A position detecting section  20  detects visual point position of operator on the basis of output of a bisected light detector  2  in an eyeball movement measurement element. A position processing section  21  determines central position of a visual point position vicinity area on the basis of information from the position detecting section  20,  and a size processing section  23  determines size of the visual point position vicinity area on the basis of output of a size adjust lever  18.  A video signal  10  is encoded by a compressing section  11  and is inputted to a code quantity reduction section  13.  A system control section  30  controls the code quantity reduction section  13  so that code quantity allocated to the area except for the visual point position vicinity area is smaller than code quantity allocated to the visual point position vicinity area to allow it to carry out reduction of code quantity. Thus, picture data can be compressed and encoded on the real time basis within a limited code quantity, and there can be obtained picture of high picture quality from a viewpoint of visual sense for user as far as possible at the time of decoding.

TECHNICAL FIELD

This invention relates to a picture compression encoding apparatus and apicture compression encoding method for compression-encoding picturedata.

BACKGROUND ART

In recent years, with realization of image in digital form and progressof picture compression technology, various picture compression encodingprocessing have been carried out. However, in the prior art, codequantity allocated to picture data of a predetermined unit is fixed to acertain fixed quantity (in the case of the fixed rate), or even in thecase of a variable rate to vary code quantity allocated to picture dataof a predetermined unit in dependency upon fineness of picture, codequantity allocated at the maximum has been already determined.Therefore, the maximum value of code quantity within a predeterminedtime is determined. As a result, when continuous complicated picturesare successive, there was limitation in the code quantity. As a matterof course, increase or decrease of code quantity allocated to thepicture leads to degree of the picture quality. In view of the above, inthe prior art, it has been carried out to control code quantity so thatthe picture quality deterioration at the time of decoding becomesminimum while taking the same code quantity as the entirety of a singlepicture by a method of allocating a larger code quantity to complicatedportions on the picture, etc.

However, way of sensing of the picture quality deterioration of viewer(viewer/listener) is changed to what portion attention is drawn withinone picture. On the other hand, the portion that the viewer carefullyobserves is the portion important within that picture, and that portionis not limited to the complicated portion within that picture. For thisreason, with the method of allocating a larger code quantity to thecomplicated portion on picture, inconvenience as described below takesplace. Namely, in the case where, e.g., the main person exists withinthe complicated background, etc., larger codes are allocated to thecomplicated background. As a result, the code quantity allocated to themain person that the viewer carefully observes is less. Thus, the viewerfeels picture quality deterioration at the time of decoding.

To cope with this, it is conceivable that the operator is permitted toarbitrarily change, every picture, allocation of code quantity withinthe picture. However, it is necessary to take much labor in order toallow the operator to set area different in allocation of code quantity,and in situations where real time characteristic such as livebroadcasting, etc. is required, such an operation is impossible.

Meanwhile, in the Japanese Patent Application Laid Open No. 44110/1995publication, there is disclosed the technology in which position ofvisual point of user is detected to display a predetermined area in thevicinity of the visual point position within one picture by highresolution, and to display other area by low resolution. In other words,it can be said that this technology is the technology in which codequantity allocated to the area in the vicinity of the visual pointposition within one picture is increased and code quantity allocated toother area is decreased. In accordance with this technology, picturequality deterioration that the user feels at the time of decoding can besuppressed while encoding respective pictures on the real time basiswithin a limited code quantity.

However, in the case where such an approach is always employed toincrease code quantity allocated to the area in the vicinity of thevisual point and to decrease code quantity allocated to other area, evenif other area is not so complicated and code quantity to be allocated isnot decreased, even in the case where quantity of codes generated is notso many, i.e., there is margin in the code quantity, there is theproblem that quantity of codes allocated to other area is necessarilyreduced and the picture quality of other area is unnecessarilydeteriorated.

Moreover, the size of the area that the viewer carefully observes withinpicture is not limited to fixed size. Accordingly, in the case where thesize of the area where quantity of codes allocated is increased iscaused to be fixed (constant), problems as described below takes place.Namely, in the case where the area that the viewer carefully observes islarger than the area where code quantity is increased, larger codequantity is allocated in the area of the center side of the area thatthe viewer carefully observes so that there results small deteriorationof the picture quality. In the area of the peripheral side of the areawhere the viewer carefully observes, code quantity to be allocatedbecomes small. As a result, deterioration of the picture quality becomeslarge. Thus, there results picture difficult to see for the viewer,i.e., picture of which picture quality has been deteriorated. To thecontrary, in the case where the area where the viewer carefully observesis smaller than the area where the code quantity is increased, a largecode quantity would be allocated also to the area except for the areawhere the viewer carefully observes. As a result, there may take placecircumstances where code quantity allocated to the area where the viewercarefully observes becomes small.

This invention has been made in view of the problems as described above,and its object is to provide a picture compression encoding apparatusand a picture compression encoding method which are capable ofcompression-encoding picture data on the real time basis within alimited code quantity, and is permitted to obtain picture (image) havinghigh picture quality from a viewpoint of visual sense for user as far aspossible at the time of decoding.

DISCLOSURE OF THE INVENTION

A picture compression encoding apparatus of this invention comprises:encoding means for compression-encoding input picture data; visual pointposition detecting means for detecting visual point position on apicture based on the input picture data; area setting means for settinga visual point position vicinity area in the vicinity of a visual pointposition detected by the visual point position detecting means; and codequantity limiting means such that when code quantity generated by theencoding means is above a predetermined quantity, it limits codequantity generated by the encoding means so that code quantity allocatedto the area except for the visual point position vicinity area set bythe area setting means is smaller than code quantity allocated to thevisual point position vicinity area.

In such a configuration, visual point position of operator on picturebased on input picture data is detected by the visual point positiondetecting means, and visual point position vicinity area is set in thevicinity of the visual point position detected by the visual pointposition detecting means on the picture based on the input picture data.Moreover, input picture data is compression-encoded by the encodingmeans, and code quantity generated by the encoding means is limited bythe code quantity limiting means by varying allocation of code quantityin dependency upon the area so that code quantity allocated to the areaexcept for the visual point position vicinity area set by the areasetting means is smaller than code quantity allocated to the visualpoint position vicinity area only when code quantity per predeterminedtime generated by the encoding means is above a predetermined quantityin the case where code quantity is not limited. Accordingly, when thereis margin in the code quantity, there is no possibility that the picturequality may be unnecessarily deteriorated. Thus, there are provided theeffects/advantages that picture data can be compression-encoded on thereal time basis within a limited code quantity and there can be obtainedpicture (image) having high picture quality from a viewpoint of visualsense for user as far as possible at the time of decoding.

Further, a picture compression encoding apparatus of this inventioncomprises: encoding means for compression-encoding input picture data;visual point position detecting means for detecting visual pointposition on a picture based on the input picture data; area settingmeans for setting visual point position vicinity area in the vicinity ofthe visual point position detected by the visual point positiondetecting means; code quantity limiting means for limiting allocation ofcode quantity in dependency upon the visual point position vicinity areaso that code quantity allocated to the area except for the visual pointposition vicinity area set by the area setting means is smaller thancode quantity allocated to the visual point position vicinity area; andarea adjustable means for changing size of the visual point positionvicinity area set by the area setting means.

In such a configuration, visual point position of operator on a picturebased on input picture data is detected by visual point positiondetecting means, and visual point position vicinity area is set in thevicinity of the visual point position detected by the visual pointposition detecting means on a picture based on input picture data. Sizeof this visual point position vicinity area is changed by area sizeadjustable means. Moreover, input picture data is compression-encoded bythe encoding means, and code quantity generated by the encoding means islimited by varying allocation of code quantity in dependency upon thearea so that code quantity allocated to the area except for the visualpoint position vicinity area set by the area setting means is smallerthan code quantity allocated to the visual point position vicinity area.Accordingly, the area where large code quantity is allocated can be setto suitable size. Thus, there can be provided the effects/advantagesthat picture data can be compression-encoded on the real time basiswithin a limited code quantity, and there can be obtained picture(image) having high picture quality from a viewpoint of visual sense foruser as far as possible at the time of decoding.

In this case, it is preferable that the code quantity limiting meansdecreases stepwise code quantity allocated to the area except for thevisual point position vicinity area toward a direction away from thevisual point position vicinity area. Thus, it is possible to avoid thatthe boundary portion of the visual point position vicinity area becomesconspicuous. As a result, picture (image) of higher picture quality froma viewpoint of visual sense can be obtained.

Moreover, it is preferable to further comprise selector means forselecting whether or not it is carried out to vary allocation of codequantity in dependency upon the area by the quantity limiting means.Thus, operator can select whether or not he carries out change ofallocation of code quantity in dependency upon the area as occasiondemands. As a result, convenience in use can be improved.

Further, the area setting means may be adapted so that when visual pointpositions are intermittently detected by the visual point positiondetecting means, visual point position vicinity areas are setcontinuously in point of time between detection time points ofrespective visual point positions. Thus, e.g., also in the case whereoperator repeatedly carefully observes plural portions within picturewith the visual point being changed in succession, visual point positionvicinity areas can be set continuously in point of time respectively inthe vicinity of plural portions where he carefully observes. As aresult, picture (image) of higher picture quality from a viewpoint ofvisual sense can be obtained.

Furthermore, the area setting means may be adapted so that the visualpoint position vicinity areas can be continuously set between the timepoint when visual point position is first detected by the visual pointposition detecting means within picture unit consisting of plural framesor plural fields and the time when the picture unit is started.Moreover, the area setting means may be adapted so that the visual pointposition vicinity areas are continuously set between the time point whenthe visual point position is detected last by the visual point positiondetecting means within picture unit consisting of plural frames orplural fields and the time when the picture unit is completed. Thus,also when the visual point position is not stable after change of sceneor before change thereof, the visual point position vicinity area can beset. As a result, picture (image) of higher picture quality from aviewpoint of visual sense can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a picturecompression encoding apparatus according to an embodiment of thisinvention.

FIG. 2 is a block diagram showing the detailed configuration of positiondetecting section in FIG. 1.

FIG. 3 is an explanatory view showing the configuration of an eyeballmovement measurement element utilized in the picture compressionencoding apparatus according to the embodiment of this invention.

FIG. 4 is an explanatory view for explaining the principle of operationof the eyeball movement measurement element shown in FIG. 3.

FIG. 5 is an explanatory view for explaining an outline of visual pointcorrection in the picture compression encoding apparatus according tothe embodiment of this invention.

FIG. 6 is an explanatory view for explaining operation by operator atthe time of encoding of video signal in the picture compression encodingapparatus according to the embodiment of this invention.

FIG. 7 is an explanatory view showing marker displayed on monitor screenin the picture compression encoding apparatus according to theembodiment of this invention.

FIG. 8 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 9 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 10 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 11 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 12 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 13 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 14 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 15 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 16 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 17 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 18 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

FIG. 19 is a flowchart for explaining the operation of the positionprocessing section in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments according to this invention will be describedbelow with reference to the attached drawings.

In a picture compression encoding apparatus according to thisembodiment, an eyeball movement measurement element is used as visualpoint position detecting means for detecting visual point position ofoperator on picture based on input picture data. Initially, this eyeballmovement measurement element will be described.

FIG. 3 is an explanatory view showing the configuration of the eyeballmovement measurement element. This eyeball movement measurement elementcomprises a light emitting diode (hereinafter referred to as LED) foremitting light of infrared rays, and a bisected light (photo) detector 2including light receiving potions 2A, 2B bisected in a horizontaldirection. While the LED 1 and the bisected light detector 2 areseparately indicated for convenience in FIGS. 3A and 3B, these membersare integrated and held from a practical point of view so that they aredisposed at the position of the lower side of the central portion of aneyeball 3 by holding member in goggle form. In this example, thebisected light detector 2 is adapted so that when operator affixes theholding member, the light receiving portion 2A is disposed at the rightside when viewed from the operator and the light receiving portion 2B isdisposed at the left side when viewed from the operator. When theoperator affixes the holding member, the LED 1 irradiates infrared raysfrom the position outside the visual field of the lower side of theeyeball 3 toward the eyeball 3 as shown in FIG. 3A, and the bisectedlight detector 2 detects reflected light from the eyeball 3 as shown inFIG. 3B.

The operation principle of the eyeball movement measurement elementshown in FIG. 3 will now be described with reference to FIG. 4. FIG. 4Ashows the state of the eyeball 3 when the visual point of operator ismoved in a right direction. Since the eyeball central portion (iris ofthe eye) 3 a has small reflection factor of light as compared to theeyeball peripheral portion (the white of the eye) 3 b, light quantityreturning to the light receiving portion 2A is smaller as compared tolight quantity returning to the light receiving portion 2B in the stateshown in FIG. 4A. FIG. 4B shows the state of the eyeball 3 when visualpoint of operator is moved in a left direction. In this state, lightquantity returning to the light receiving portion 2B becomes smaller ascompared to light quantity returning to the light receiving portion 2A.Accordingly, it becomes possible to detect movement in the horizontaldirection of the eyeball 3, in other words, movement in the horizontaldirection of the visual point from difference between output of thelight receiving portion 2A and output of the light receiving portion 2B.

FIG. 4C shows the state of the eyeball 3 when the visual point ofoperator is moved in an upper direction. In this state, respective raysof light returning to the light receiving portions 2A, 2B are bothincreased. FIG. 4D shows the state of the eyeball 3 when the visualpoint of operator is moved in a lower direction. In this state,respective rays of light returning to the light receiving portions 2A,2B are both decreased. Accordingly, it is possible to detect movement inthe vertical direction of the eyeball 3, in other words, movement in thevertical direction of the visual point from sum of output of the lightreceiving portion 2A and output of the light receiving portion 2B.

In this way, position of the visual point of operator can be detectedfrom difference between outputs of the light receiving portions 2A, 2Band sum thereof. While the operation principle of the eyeball movementmeasurement element has been described above, since reflected lightquantity at the eyeball 3 changes every operators in practice, such anapproach is employed to fix position of the head of operator to allowhim to carefully observe positions of several points determined inadvance on picture to carry out correction of visual point position(hereinafter referred to as visual point correction) on the basis ofoutputs of the light receiving portions 2A, 2B at that time.

Outline of the visual point correction will now be described withreference to FIG. 5. In this case, the portion in the lateral direction(x-direction) on picture 5 is divided into 640 sections and the portionin the longitudinal direction (y-direction) is divided into 480sections. When the left and upper portion of the picture 5 is assumed tobe origin, position in the lateral direction is represented by m,position in the longitudinal direction is represented by n, and positionof an arbitrary point on the picture is represented by P (m, n). At thetime of visual point correction, markers 6 are displayed in successionat, e.g., at nine points described below, i.e., P(10, 10), P(320, 10),P(630, 10), P(10, 240), P(320, 240), P(630, 240), P(10, 470), P(320,470) and P(630, 470) to allow operator 7 who has affixed holding member8 to which the eyeball movement measurement element has been attached tocarefully observe respective points indicated by markers 6. Thus, visualpoint correction is carried out on the basis of outputs of the lightreceiving portions 2A, 2B at that time.

FIG. 1 is a block diagram showing the configuration of the picturecompression encoding apparatus according to this embodiment. Thispicture compression encoding apparatus comprises a compressing section11 supplied with a video signal 10 to compression-encode this videosignal 10, a delay element 12 for delaying, by a predetermined time,output data of this compressing section 11, and a code quantityreduction section 13 supplied with output data from this delay element12 to vary allocation of code quantity in dependency upon the area asoccasion demands so that code quantity allocated to the area except forthe visual point position vicinity area is smaller than code quantityallocated to the visual point position vicinity area to thereby carryout reduction of code quantity to output encoded data 14. Thecompressing section 11 carries out compression processing of videosignals by using Discrete Cosine Transform (hereinafter referred to asDCT) utilizing the spatial correlation and bidirectional predictiveencoding utilizing the correlation in point of time as employed in,e.g., MPEG (Moving Picture Experts Group) standard. In this case, thecompressing section 11 carries out DCT processing in predetermined pixelblock units to quantize coefficients after undergone DCT processing tofurther allow quantized data to undergo variable length encoding tooutput encoded data. It is to be noted that there may be employed aconfiguration such that variable length encoding is carried out at thecode quantity reproduction section 13 and the compressing section 11outputs quantized data.

The picture compression encoding apparatus further comprises a switch 16for change for allowing operator to designate timing, etc. of change ofscene, a switch 17 for interruption, which gives instruction(designation) to interrupt change of allocation of code quantity independency upon the area at the code quantity reduction section 13, anda size adjust lever 18 for changing size of the visual point positionvicinity area.

The picture compression encoding apparatus further comprises a positiondetecting section 20 for detecting visual point position of operator onthe basis of output signals of the respective light receiving portions2A, 2B of the bisected light detector 2, a position processing section21 for carrying out processing for determining central position of thevisual point position vicinity area on the basis of position informationoutputted from this position detecting section 20, a delay element 22for delaying output signal of the size adjust lever 18 by timecorresponding to processing time at the position processing section 21,and a size processing section 23 for carrying out processing todetermine size of the visual point position vicinity area on the basisof output signal of this delay element 22.

The picture compression encoding apparatus further comprises a markerinsertion section 24 for determining position and size of marker onpicture from position information from the position detecting section 20and output signal of the size adjust lever 18 to superimpose signal formarker display on the video signal 10 to output it as an output videosignal 25 for monitor.

The picture compression encoding apparatus further comprises acorrelation detecting section 26 supplied with output data of thecompressing section 11 to examine correlation between current pictureand previous picture, a switching processing section 27 supplied withoutput data of this correlation detecting section 26, output signal ofthe change switch 16 and switching signal 28 from switcher (not shown)used for camera switching to determine timing of change of scene, and asystem control section 30 for controlling the entirety of the picturecompression encoding apparatus.

The system control section 30 is supplied with respective output data ofthe compressing section 11, the position processing section 21, the sizeprocessing section 23 and the switching processing section 27, andrespective output signals of the change switch 16 and the interruptionswitch 17, and is further supplied with switching select signal 31 andvisual point correction mode signal 32 inputted through switch, etc.(not shown) and prescribed code quantity data 33 inputted throughinterface (not shown). In addition, the system control section 30outputs code quantity reduction control signal 35 to the code quantityreduction section 13, and controls the marker insertion section 24 andthe switching processing section 27.

The position processing section 21 is also supplied with output signalof the interruption switch 17 and output data of the switchingprocessing section 27. Moreover, the size processing section 23 is alsosupplied with respective output data of the position processing section21 and the switching processing section 27.

The position processing section 21, the size processing section 23, thecorrelation detecting section 26, the switching processing section 27and the system control section 30 are constituted by, e.g.,microcomputer.

FIG. 2 is a block diagram showing the detailed configuration of theposition detecting section 20 in FIG. 1. This position detecting section20 comprises a subtracter 41 for generating difference signal betweensignals after undergone current-voltage conversion of the lightreceiving portions 2A, 2B at the bisected light detector 2, an adder 42for generating sum signal of signals after undergone current-voltageconversion of the light receiving sections 2A, 2B, an analog-digital(hereinafter referred to as A/D) converter (1) 43 for converting outputsignal of the subtracter 41 into, e.g., digital signal of 8 bits, an A/Dconverter (2) 44 for converting output signal of the adder 42 into,e.g., digital signal of 8 bits, and a divider 45 for dividing outputsignal of the A/D converter (1) 43 by output signal of the A/D converter(2) 44. Output signal of the divider 45 and output signal of the A/Dconverter (2) 44 are inputted to the system control section 30. Thesystem control section 30 calculates, at the time of visual pointcorrection, correction value for carrying out conversion into referencevalues at respective positions indicated by the marker 6 on the basis ofoutput signal of the divider 45, output signal of the A/D converter (2)44 and position information of the marker 6 (FIG. 5) that the systemcontrol section 30 generates to output this correction value in a mannercaused to correspond to respective output values of the divider 45 andthe AID converter (2) 44.

The position detecting section 20 further comprises a RAM (Random AccessMemory) (1) 47 for storing correction value with respect to outputsignal of the divider 45 outputted from the system control section 30 atthe time of visual point correction to output correction value incorrespondence with output signal of the divider 45 at the time ofencoding of video signal 10, a RAM (2) 48 for storing correction valuewith respect to output signal of the A/D converter (2) 44 outputted fromthe system control section 30 at the time of encoding of video signal 10to output correction value in correspondence with output signal of theA/D converter (2) 44 at the time of encoding of the video signal 10, amultiplier (1) 49 for multiplying, at the time of encoding of videosignal 10, output signal of the divider 45 by correction value outputtedfrom the RAM (1) 47, a multiplier (2) 50 for multiplying, at the time ofencoding of the video signal 10, output signal of the A/D converter (2)44 by correction value outputted from the RAM (2) 48, a ROM (Read OnlyMemory) (1) 51 for converting output signal of the multiplier (1) 49into position information in the lateral direction on picture, and a ROM(2) 52 for converting output signal of the multiplier (2) 50 intoposition information in the longitudinal direction on the picture.Output information of the ROMs 51, 52 are inputted to the system controlsection 30, and are sent to the position processing section 21 in FIG.1.

The operation of the picture compression encoding apparatus according tothis embodiment will now be described. Initially, the operation at thetime of visual point correction will be explained. Whether or not theoperation of the visual point correction is executed is designated byvisual point correction mode signal 32 inputted to the system controlsection 30. At the time of visual point correction, a control signal toinstruct insertion of the marker 6 is sent to the marker insertionsection 24 from the system control section 30. The marker insertionsection 24 superimposes, in accordance with this control signal, signalfor display of marker 6 on the video signal 10 so that marker 6 isinserted at the position prescribed in advance on the picture to outputit as output video signal 25 for monitor. When visual point is incorrespondence with marker 6 on the picture, operator turns ON thechange switch 16. The system control section 30 is operative so thatwhen the change switch 16 is turned ON, it calculates correction valueon the basis of respective output signals of the divider 45 and the A/Dconverter (2) 44 and position information of the marker 6 at that timeto allow the RAMs 47, 48 to store this correction value in a mannercaused to correspond to respective output values of the divider 45 andthe A/D converter (2) 44. When the change switch 16 is turned ON, thesystem control section 30 successively switches position of the marker 6by control signal. When the above-mentioned operation is repeated sothat measurements at 9 (nine) portions shown in FIG. 5 are successivelycompleted, correction values are all calculated.

The operation at the time of encoding of video signal in the picturecompression encoding apparatus according to this embodiment will now bedescribed. This operation is executed except that the operation ofvisual point correction is designated by the visual point correctionmode signal 32. Initially, the operation by operator at the time ofencoding of video signal will be described with reference to FIG. 6. Atthe time of encoding of video signal, the operator 7 who has affixed theholding member 8 to which eyeball movement measurement element isattached operates his own visual point, the change switch 16, theinterruption switch 17 and the size adjust lever 18. Namely, theoperator 7 changes the visual point while looking at marker 61 appearingon picture 5, and designates, by size adjust lever 18, size of thevisual point position vicinity area which is the area where a large codequantity is allocated. As a result, marker 61 for visual point positionindicating visual point position is displayed on the picture 5, andframe shaped, e.g., rectangular range designation marker 62 indicatingthe range of the visual point position vicinity area is displayed at theperiphery of the marker 61. When the operator 7 moves the visual point,markers 61, 62 both move on the picture 5 in a manner following thevisual point. Moreover, when the operator 7 operates the size adjustlever 18, size of the marker 62 is changed. Examples of display ofmarkers 61, 62 are shown in FIGS. 7A to 7D in connection with four kindsof states where size of the marker 62 is different. Further, when sceneof image displayed on the picture 5 is changed (switched), the operator7 turns ON the change switch 16 to thereby designate timing of change(switching) of scene. In addition, in the case where particularlyimportant portion does not exist on the picture 5, etc., the operator 7turns ON the interruption switch 17, thereby making it possible tointerrupt that a larger code quantity is allocated to the visual pointposition vicinity area.

At the time of encoding of video signal, signals after undergonecurrent-voltage conversion of the light receiving portions 2A, 2B at thebisected light detector 2 are inputted in succession to the positiondetecting section 20 shown in FIG. 2. At the position detecting section20, difference signal and sum signal are generated by the subtracter 41and the adder 42. The difference signal and the sum signal arerespectively converted into digital signals by the A/D converters 43,44. Moreover, output signal of the A/D converter (1) 43 is divided byoutput signal of the A/D converter (2) 44 by the divider 45. Outputsignal of the divider 45 is inputted to the RAM (1) 47 and themultiplier (1) 49, and output signal of the A/D converter (2) 44 isinputted to the RAM (2) 48 and the multiplier (2) 50. The multiplier (1)49 multiplies output signal of the divider 45 by correction valueoutputted from the RAM (1) 47 to make correction thereof, and themultiplier (2) 50 multiplies output signal of the A/D converter (2) 44by correction value outputted from the RAM (2) 48 to make correctionthereof. Respective output signals of the multipliers 47, 48 arerespectively converted into position information in the lateraldirection and in the longitudinal direction on the picture by the ROMs51, 52, and this position information is sent to the position processingsection 21 and the marker insertion section 24.

The marker insertion section 24 determines positions and sizes ofmarkers 61, 62 on the picture from position information from theposition detecting section 20 and output signal of the size adjust lever18 to superimpose signal for marker display on the video signal 10 tooutput it as monitor output video signal 25. On the basis of thismonitor output video signal 25, markers 61, 62 are displayed on picturebased on the video signal 10 at the monitor in a superimposed manner. Onthe other hand, at the position processing section 21, processing fordetermining central position of the visual point position vicinity areais carried out as described later in detail.

Moreover, output signal of the size adjust lever 18 is delayed, by thedelay element 22, by time corresponding to processing time at theposition processing section 21, and is inputted to the size processingsection 23. At this size processing section 23, processing fordetermining size of the visual point position vicinity area is carriedout. In this example, at the size processing section 23, when the visualpoint position is fixed, high frequency component of size change is cuton the basis of output data of the position processing section 21. Thus,size change by very small movement of the hand can be suppressed.

The video signal 10 to be encoded is compressed and encoded(compression-encoded) by the compressing section 11, and output data ofthis compressing section 11 is inputted to the code quantity reductionsection 13 in the state delayed by time corresponding to the processingtime at the position processing section 21 and the size processingsection 23 by the delay element 12.

Moreover, output data of the compressing section 11 is also inputted tothe correlation detecting section 26, and correlation between currentpicture and previous picture is examined by this correlation detectingsection 26. In this example, the correlation detecting section 26 takesdifference between lower frequency component of coefficients which havebeen caused to undergo DCT processing at the compressing section 11 ofcurrent picture and that of the previous picture to judge thatcorrelation is small when this difference is large (change of the lowerfrequency component is large). Output data of the correlation detectingsection 26 is inputted to the switching processing section 27. Theswitching processing section 27 is supplied with output signal of thechange switch 16 and switching signal 28 from switcher in addition tothe above. The switching processing section 27 is operative so that whenswitching select signal 31 inputted to the system control section 30takes mode of switch of operator, it determines timing of change ofscene on the basis of output data of the correlation detecting section26 and output signal of the change switch 16. In more practical sense,the switching processing section 27 is operative to assume the timepoint when the change switch 16 is turned ON as the origin to select, aspicture of change of sense, picture in which there is large change ofthe lower frequency component (correlation is small) of DCT coefficientsfor time period from −1.0 to 0 sec. as compared to the previous picture.In addition, in the case where change of correlation for the time periodfrom −1.0 to 0 sec. is small, −0.33 sec. is assumed to be change ofscene.

Moreover, the switching processing section 27 is operative so that whenswitching select signal 31 inputted to the system control section 30takes camera mode, it assumes timing of input of switching signal 28from switcher used for camera switching as change of scene.

The scene change signal which is output data of the change (switching)processing section 27 indicating change of scene is inputted to thesystem control section 30, the position processing section 21 and thesize processing section 23. As described in detail later, the positionprocessing section 21 is operative so that when visual point positionsare intermittently detected by the position detecting section 20 under apredetermined positional relationship, interpolation processing iscarried out so that visual point position vicinity areas arecontinuously set in point of time for time period between detection timepoints of respective visual point positions. This interpolationprocessing is carried out in scene units. Further, the positionprocessing section 21 carries out interpolation processing so thatvisual point position vicinity areas are continuously set in point oftime for time period between the detection time point of the firstvisual point position within one scene and the starting time of sceneunder a predetermined condition, and carries out interpolationprocessing so that visual point position vicinity areas are continuouslyset in point of time for time period between the detection time point ofthe last visual point position within one scene and the end time ofscene under a predetermined condition. The size processing section 23also carries out interpolation processing similar to the positionprocessing section 21.

The system control section 30 compares code quantity per predeterminedtime by output data of the compressing section 11 and prescribed valueof code quantity prescribed in advance by prescribed code quantity data33, whereby only in the case where code quantity per predetermined timeby output data of the compressing section 11 is above prescribedquantity, it outputs code quantity reduction control signal 35 to thecode quantity reduction section 13 to allow the code quantity reductionsection 13 to carry out reduction of code quantity so that code quantityper predetermined time outputted from the code quantity reductionsection 13 is not above the prescribed value. At this time, the systemcontrol section 30 sets visual point position vicinity area on the basisof output data of the position processing section 21 and output data ofthe size processing section 23 to vary allocation of code quantity independency upon the area so that code quantity allocated to the areaexcept for the visual point position vicinity area is smaller than codequantity allocated to the visual point position vicinity area. Reductionof code quantity is carried out by successively decreasing, in orderfrom the higher frequency band side of coefficients after undergone DCTprocessing, the numbers of bits allocated to those coefficients. In thiscase, in order to avoid that the boundary portion of the visual pointposition vicinity area becomes conspicuous, reduction of code quantityis carried out stepwise from the visual point position vicinity areatoward the outside. For example, the number of bits allocated isdecreased by one 1 bit in succession every pixel block where DCTprocessing is carried out from the visual point position vicinity areatoward the external. In this way, reduction of code quantity is carriedout as occasion demands. As a result, encoded data 14 outputted from thecode quantity reduction section 13 is outputted to the outside as outputdata of the picture compression encoding apparatus. This output data is,e.g., transmitted to communication network, or is recorded onto therecording medium.

The position processing at the position processing section 21 will bedescribed in detail with reference to the flowcharts of FIGS. 8 to 19.This position processing is assumed to be, e.g., 500 ms (½ sec.). Theprocessing content of the position processing roughly consists of threekinds of processing of point processing for specifying visual pointposition in the case where visual point is fixed, vector processing fordetermining movement vector of visual point position in the case wherethe visual point is moving, and interruption processing for interruptingthat a larger code quantity is allocated to the visual point positionvicinity area. Hereinafter, visual point position determined by thepoint processing is represented by point P (i, p(i)), vector determinedby the vector processing is represented by V (i, v(i)), and state of theinterruption processing is represented by N (i, n(i)). In this case, irepresents time after scene has been changed, and the i-th time meansprocessing for time period of i/2 to (i+1)/2 sec. after the scene hasbeen changed. p(i), v(i), n(i) respectively indicate to what processingcurrent processing corresponds within the same unit time t. Since theinterpolation processing is carried out as described later at the timeof movement of visual point, plural point processing and vectorprocessing are carried out within the same unit time t. The case ofp(i)=0 and v(i)=0 represents actual visual point position where nointerpolation processing is carried out. The case of p(i)≠0 and v(i)≠0represents processing based on the interpolation processing. Moreover,in the case of the interruption processing, even if interpolationprocessing is implemented, there are instances where the interruptionprocessing is carried out within the same unit time t and there areinstances where the interruption processing is not carried out withinthe same unit time t. However, since whether or not the interruptionprocessing is carried out is determined at the timing when theinterruption switch 17 is turned ON as described later, the state whereno interruption processing is carried out and the state where theinterruption switch 17 is pushed down (is tuned ON) is represented byn(i)=1 and the state where the interruption processing is carried out isrepresented by n(i)=0.

As shown in FIG. 8, in the position processing, p(i), v(i) and n(i) areall cleared (are caused to be 0) (step S101). Similarly, i is cleared(is caused to be 0) (step S102). Then, i+1 is caused to be newly i (stepS103) to judge whether or not change of scene takes place (step S104).Change information of scene is obtained from change processing section27. In the case where scene has been changed (Y), the operationprocessing shifts to end processing (FIGS. 15 to 19) which will bedescribed later. In the case where scene is not changed (N), the stateof the interruption switch 17 is confirmed (step S105). In the casewhere the interruption switch 17 is pushed down (is turned ON), theoperation processing shifts to interruption switch processing (FIG. 14)which will be described later. In the case where the interruption switch17 is not pushed down (is in OFF state), whether or not the visual pointmovement distance is small or large is judged (step S106). In this case,it is assumed that visual point movement distance within unit time t isdetermined, whereby in the case where this visual point movementdistance is within 20×20 in terms of pixels on the picture, it is judgedthat the visual point movement distance is small, and in the case exceptfor the above, it is judged that the visual point movement distance islarge. In the case where the visual point movement distance is small,the visual point is assumed to be fixed to shift to point processing(FIG. 9) which will be described later. In the case where the visualpoint movement distance is large, whether movement velocity of thevisual point is high or low is judged (step S107). In this case, such anapproach is employed to judge movement velocity of the visual point onthe basis of movement distance between frames ({fraction (1/30)} sec.).In the case where the visual point is moved in the longitudinaldirection or in the lateral direction by 100 pixels or more betweenframes within the unit time t, it is assumed to be judged that movementvelocity of the visual point is high. In the case except for the above,it is assumed to be judged that movement velocity of the visual point islow. In the case where movement velocity of the visual point is high, itis assumed that the visual point is moving to return to the step S103without carrying out processing within unit time t to update i. It is tobe noted that since such high speed moving body moving in thelongitudinal direction or in the lateral direction by 100 pixels or morebetween frames cannot be followed by the eye of the human being on thepicture, there is no necessity of carrying out processing to allocate alarger code quantity to the visual point position vicinity area. In thecase where movement velocity of the visual point is low, the operationprocessing shifts to vector processing (FIGS. 11, 12) which will bedescribed later.

In the point processing shown in FIG. 9, such an approach is employed tofirst determine average value of visual point positions (visual pointaverage position) within unit time t to assume this average value aspoint P(i, p(i))=(m_(i0), n_(i0)) determined by processing within theunit time t (step S201). In this case, the visual point average positionis determined by averaging visual point positions every frame, forexample. Moreover, m_(i0) is assumed to be position in the lateraldirection on the picture and n_(i0) is assumed to be position in thelongitudinal direction on the picture. Then, whether or notinterpolation processing is carried out is judged. Since theinterpolation processing is unnecessary when the portion in the vicinityof the same point is continuously viewed, whether or not theinterpolation processing is carried out is judged on the basis ofdistance between current point and point determined by the processing atthe unit time t earlier by one. As distance between points, there isused value PD (x, y) obtained by adding square of difference betweenrespective positions in the lateral and longitudinal directions. In thiscase, x, y represent i at the time of determination of respectivepoints. PD (x, y) is represented by the following formula.

PD(x,y)=(m _(x0) −m _(y0))²+(n _(x0) −n _(y0))²

In more practical sense, initially, variable j is set to 1 (step S202).Then, whether or not PD(i, i−j) is smaller than fixed distance PD_(ref)is judged (step S203). In this case, PD_(ref) is set to 1800. In thecase where PD (i, i−j) is smaller than PD_(ref) (Y), it is assumed thatthe portion in the vicinity of the same point is continuously viewed toreturn to the step S103 (FIG. 8) without carrying out interpolationprocessing to update i for the purpose of shifting to the processing atthe next unit time t. On the other hand, in the case where PD(i, i−j) isPD_(ref) or more (N), whether or not the portion previously viewedexists in the vicinity of the point at the time of current processing isjudged. This is carried out by judging whether or not there exists pointdetermined by the previous point processing or end point position ofvector determined by the previous vector processing within predeterminedtime TD_(max) (assumed to be 5 sec. in this case). In this case, in thevector processing, vector V(i, v(i)) is represented by initial point andend point, and when v(i)=0 which is not the interpolation processing,vector V(i, v(i)) is represented by the following formula. In thisformula, position of the initial point is assumed to be (ms_(i0),ns_(i0)) and position of the end point is assumed to be (me_(i0),ne_(i0)).

V(i,v(i))=(ms _(i0) , ns _(i0) , me _(i0) , ne _(i0))

The judgment as to whether or not there exists the portion previouslyviewed in the vicinity of point at the time of current processing iscarried out as follows in more practical sense. Namely, initially, j+1is newly set to j (step S204) to judge whether t_(i)−t_(i−1) is aboveTD_(max) or i=j, or corresponds to the case except for the above isjudged (step S205). In the case except for the above, i.e., in the casewhere t_(i)−t_(i−1) is within TD_(max) and i=j does not hold (N),whether PD(i, i−j) is smaller than fixed distance PD_(ref), or distanceVED(i, i−j) between point at the time of current processing and endpoint of vector determined by the previous vector processing is smallerthan fixed distance PD_(ref), or corresponds to the case except for theabove is judged (step S206). In this case, VED(x, y) is represented bythe following formula.

VED(x,y)=(m _(x0) −me _(y0))²+(n _(x0) −ne _(y0))²

In the case where PD(i, i−j) is smaller than PD_(ref), or VED(i, i−j) issmaller than PD_(ref) (step S206; Y), interpolation processing of point(FIG. 10) is carried out. In the case except for the case where PD(i,i−j) is smaller than PD_(ref), or VED(i, i−j) is smaller than PD_(ref)(step S206; N), whether or not N(i−j, 0) exists is judged (step S207).If N(i−j, 0) exists (Y), it is considered that the interruptionprocessing is carried out. Accordingly, this processing is separatedfrom the previous portion. Namely, the operation processing returns tothe step S103 (FIG. 8) without carrying out the interpolation processingto update i for the purpose of shifting to the processing at the nextunit time t. If N(i−j, 0) does not exist (N), the operation processingreturns to the step S204.

In the case where the portion viewed previously exists in the vicinityof point at the time of current processing as stated above, theinterpolation processing is carried out. As a result, visual pointposition vicinity areas are set continuously in point of time in thevicinity of point at the time of current processing. As occasiondemands, such a processing to allocate a larger code quantity to thevisual point position vicinity area is carried out. Thus, in the casewhere, e.g., operator carefully observes in a repeated manner, whilechanging the visual point, in succession, plural portions within thepicture, visual point position vicinity areas are set continuously inpoint of time respectively in the vicinity of carefully observed pluralportions.

In the case where the portion previously viewed cannot be found out inthe vicinity of point at the time of current processing within fixedtime TD_(max) or for a time period until the starting time of scene(step S205; Y), whether or not the time i after scene has been changedis within the prescribed time TS is judged (step S208). In the casewhere the time i after scene has been changed is above the prescribedtime TS (N), the operation processing returns to the step S103 (FIG. 8)without carrying out the interpolation processing to update i for thepurpose of shifting to processing at the next unit time t. In the casewhere the time i after scene has been changed is within the prescribedtime TS (step S208; Y), position of point P (1, p(1)) at i=1 is causedto be the same as position (m_(i0), n_(i0)) of point at the time ofcurrent processing (step S209) for the purpose of carrying outprocessing to shift to the interpolation processing (FIG. 10) of pointto carry out interpolation processing of point for a time period fromthe starting time of scene to the time of current processing.

FIG. 10 shows the interpolation processing of point. In thisinterpolation processing of point, variable k is initially set to 0(step S301) thereafter to allow k+1 to be newly k (step S302) thereafterto judge whether or not k=j holds (step S303). In the case where k=jdoes not hold (N), p(i−k)+1 is caused to be newly p(i−k) (step S304).Namely, the number of processing operations is incremented by 1. Then,whether or not i−j=0 is judged (step S305). In the case of i−j=0 (Y),points at the time of current processing are filled for a time periodfrom the starting time of scene up to current processing time. Namely,interpolation value P(i−k, p(i−k)) of point is caused to be the same asposition (m_(i0), n_(i0)) of point at the time of current processing toadd this interpolation value (step S306) to shift to step S302. In thecase where i−j=0 does not hold (step S305; N), whether or not P(i, 0)and P(i−j, 0) exist is judged (step S307). In the case where P(i, 0) andP(i−j, 0) exist (Y), i.e., in the case where interpolation processing iscarried out between point at the time of current processing and point atthe previous time processing of (i−j), since two points have very closepositional relationship, interpolation value P (i−k, p(i−k)) of point iscaused to be center value between two points ((m_(i0)+m_((i−j)0))/2,(n_(i0)+n_((i−j)0)/2) to add this interpolation value (step S308) toreturn to the step S302. In the case except for the case where P(i, 0)and P(i−j, 0) exist (step S307; N), whether or not P(i, 0) and V(i−j, 0)exist is judged (step S309). In the case where P(i, 0) and V(i−j, 0)exist (Y), i. e., in the case where interpolation processing is carriedout between point at the time of current processing and end point ofvector at the time of previous processing of (i−j), since two pointshave very close positional relationship, interpolation value P of point(i−k, p(i−k)) is caused to be center value between two points((m_(i0)+me_((i−j)0))/2, (n_(i0)+ne_((i−j)0))/2) to add thisinterpolation value (step S310) to return to the step S302. In the caseexcept for the case where P(i, 0) and V(i−j, 0) exist (step S309; N),there results (is carried out) interpolation processing between initialpoint of vector at the time of current processing and point at theprevious time of processing of (i−j). Also in this case, since twopoints have very close positional relationship, interpolation value P ofpoint (i−k, p(i−k)) is caused to be center value between two points((ms_(i0)+m_((i−j)0))/2, (ns_(i0)+n_((i−j)0))/2) to add thisinterpolation value (step S311) to return to the step S302. When thereresults k=j (step S303; Y), the interpolation processing of point iscompleted to return to the step S103 (FIG. 8).

FIGS. 11 and 12 show vector processing. An average value of visual pointposition vectors within unit time t (average visual point movementvector) is first determined to allow this average value to be vectorV(i, v(i)) determined by processing within the unit time t (step S401).The average visual point movement vector is determined, e.g., bydetermining average value of vectors of visual point movement betweenrespective frames within the unit time t to multiply this average vectorby 15 times with the center of the average vector being as reference.Then, similarly to the case of the point processing, whether or not theinterpolation processing is carried out is judged. Namely, since theinterpolation processing is unnecessary when the visual point iscontinuously moving while seeking for the same object, there is judgedwhether or not the interpolation processing is carried out on the basisof distance between initial point of vector at the time of currentprocessing and end point of vector determined by processing earlier byone. As distance between initial point of vector at the time of currentprocessing and end point of vector determined by processing earlier byone, there is used value VD(x, y) obtained by adding square ofdifferences between respective positions in the lateral direction and inthe longitudinal direction. In this case, x, y represent i at the timeof determination of respective vectors. VD(x, y) is represented by thefollowing formula.

VD(x,y)=(ms _(x0) −me _(y0))²+(ns _(x0) −ne _(y0))²

In more practical sense, initially, variable j is set to 1 (step S402).Then, whether or not VD(i, i−j) is smaller than predetermined distanceVD_(ref) is judged (step S403). In this case, similarly to PD_(ref),VD_(ref) is set to 1800. In the case where VD(i, i−j) is smaller thanVD_(ref) (Y), the vector is assumed to be continuous to return to thestep 103 (FIG. 8) without carrying out the interpolation processing toupdate i for the purpose of shifting to the processing at the next unittime t. On the other hand, in the case where VD(i, i−j) is VD_(ref) ormore (N), j+1 is caused to be newly j (step S404) to judge whethert_(i)−t_(i−j) is above TD_(max) or i=j, or corresponds to the caseexcept for the above (step S405). In the case except for the above,i.e., in the case where t_(i)−t_(i−j) is within TD_(max) and i=j doesnot hold (N), there is judged continuity of vector at the time ofcurrent processing and vector determined by previous vector processingor point determined by the previous point processing.

In more practical sense, initially, as shown in FIG. 12, whether V(i−j,0) exists is judged (step S407). In the case where V(i−j, 0) exists (Y),continuity of vector at the time of current processing and vectordetermined by the previous vector processing is judged. In the case ofthe vector processing, continuity of vector is judged by differencebetween initial point of vector at the time of current processingpredicted from previous vector and initial point of actual vector at thetime of current processing, or difference between initial point of theprevious vector predicted from vector at the time of current processingand initial point of previous actual vector. In this case, continuity ofvector is assumed to be judged by difference between initial point ofthe previous vector predicted from vector at the time of currentprocessing and initial point of the previous actual vector. In thiscase, initial points of previous vectors predicted from vector at thetime of current processing (hereinafter referred to as vector initialpoint predictive value) mc_(ij), nc_(ij) can be determined by shifting(in point of time) vector at the time of current processing by timedifference as it is, and are expressed by the following formulas.

mc _(xy) =ms _(x0)−(x−y)×(me _(x0) −ms _(x0))

nc _(xy) =ns _(x0)−(x−y)×(ne _(x0) −ns _(xo))

VCD(x, y) representing distance between vector initial point predictivevalues mc_(xy), nc_(xy) and initial point of the previous actual vectoris represented by the following formula.

VCD(x,y)=(mc _(xy) −ms _(y0))²−(nc _(xy) −ns _(y0))²

Accordingly, in the case where V(i−j, 0) exists (step S407; Y), whetheror not VCD(i, i−j) is smaller than PD_(ref) is judged (step S408). Inthe case where VCD(i, i−j) is smaller than PD_(ref) (Y), interpolationprocessing of vector (FIG. 13) is carried out. In the case where V(i−j,0) does not exist (step S407; N) or VCD(i, i−j) is PD_(ref) or more(step S408; N), whether or not P(i−j, 0) exists is judged (step S409).In the case where P(i−j, 0) exists (Y), continuity of vector at the timeof current processing and point determined by the previous pointprocessing is judged.

In this case, distance VSD(x, y) between initial point of vector at thetime of current processing and the previous point and VSCD(x, y)representing distance between vector initial point predictive valuesmc_(xy), nc_(xy) and the previous point are defined by the followingformulas.

VSD(x,y)=(ms _(x0) −m _(y0))²+(ns _(x0) −n _(y0))²

VSCD(x,y)=(mc _(xy) −m _(y0))²+(nc _(xy) −n _(y0))²

In the case where P(i−j, 0) exist (step S409; Y), whether or not VSD (i,i−j) is smaller than PD_(ref) is initially judged (step S410). In thecase where VSD(i, i−j) is smaller than PD_(ref) (Y), interpolationprocessing of point (FIG. 10) is carried out. In the case where VSD(i,i−j) is PD_(ref) or more (N), whether or not VSCD(i, i−j) is smallerthan PD_(ref) is judged (step S411). In the case where VSCD(i, i−j) issmaller than PD_(ref) (Y), interpolation processing of vector (FIG. 13)is carried out.

In the case where P(i−j, 0) does not exist (step S409; N) or in the casewhere VSCD(i, i−j) is PD_(ref) or more (step S411; N), whether or notN(i−j, 0) exists is judged (step S412). If N(i−j, 0) exists (Y), sincethe interruption processing is assumed to be carried out, currentprocessing is separated from the portion earlier than that. Namely, theoperation processing returns to the step S103 (FIG. 8) without carryingout the interpolation processing to update i for the purpose of shiftingto the processing at the next unit time t. If N(i−j, 0) does not exist(N), the operation processing returns to the step S404 (FIG. 11).

In the case where there is continuity between vector at the time ofcurrent processing and vector determined by the previous vectorprocessing or point determined by the previous point processing, theinterpolation processing is carried out so that visual point positionvicinity areas are set continuously in point of time. Thus, in the casewhere, e.g., operator alternately carefully observes object movingwithin picture on screen and other object (either fixed object or movingobject may be employed), visual point position vicinity areas are setcontinuously in point of time respectively with respect to pluralobjects which have been carefully observed.

In the case where interpolation processing is not carried out similarlyto the point processing (step S405; Y), whether or not time i after thescene has been changed is within the prescribed time TS is judged (stepS406 of FIG. 11). In the case where the time i after the scene has beenchanged is above the prescribed time TS (N), the operation processingreturns to the step S103 (FIG. 8) without carrying out interpolationprocessing to update i for the purpose of shifting to processing at thenext unit time t. In the case where the time i after the scene has beenchanged is within the prescribed time TS (step S406; Y), the operationprocessing shifts to the interpolation processing of vector (FIG. 13) tocarry out interpolation processing of vector for a time period from thestarting time of scene to the current processing time.

FIG. 13 shows interpolation processing of vector. In the interpolationprocessing of vector, variable k is initially set to 0 (step S501)thereafter to allow k+1 to be newly k (step S502) thereafter to judgewhether or not k=j holds (step S503). In the case where k=j dose nothold (N), v(i−k)+1 is caused to be newly v(i−k) (step S504). Namely, thenumber of processing operations is incremented by 1. Then, whether ornot i−j=0 holds is judged (step S505). In the case of i−j=0 (Y),interpolation values of vectors are added for a time period from thestarting time of scene up to the current processing time to fill vectorsarriving at the visual point at the current processing time (step S506)to return to the step S502. Interpolation value of vector is valueobtained by extending vector at the current processing time. Thus, it issufficient to replace initial points of respective certain vectors byend point of vector earlier by one in order retroactively in point oftime to prepare end points of respective vectors earlier by one, and toshift retroactively time by difference between end point and initialpoint of vector at the current processing time from the prepared endpoint to prepare initial points of respective vectors earlier by one.Interpolation value of vector V(i−k, v(i−k)) is represented by thefollowing formula in more practical sense.

V(i−k,v(i−k))=(ms0 _(i−k) ,ns0 _(i−k) ,me0 _(i−k) , me0 _(1−k))

In the above formula,

ms0 _(i−k) =ms _(i−k+1 v(i−k+1))−(ms _(i0) −me _(i0))

ns0 _(i−k) =ns _(i−k+1 v(i−k+1))−(ns _(i0) −ne _(i0))

 me0 _(i−k) =ms _(i−k+1 v(i−k+1))

ne0 _(i−k) =ns _(i−k+1 v(i−k+1))

In the case where i−j=0 does not hold (step S505; N), whether or notV(i−j, 0) exists is judged (step S507). In the case where V(1−j, 0)exists (Y), i.e., in the case where interpolation processing is carriedout between vector at the current processing time and vector at theprevious processing time of (i−j), initial points of respective vectorsat the current processing time and end points of respective previousvectors are connected to divide them every unit time required forpassing through the distances therebetween to determine interpolationvalues of respective vectors to add interpolation values of vectors(step S508) to return to the step S502. Interpolation value V of vector(i−k, v(i−k)) is represented by the following formula in more practicalsense.

V(i−k,v(i−k))=(msv _(i−k) , nsv _(i−k) , mev _(i−k) , nev _(i−k))

In the above mentioned formula,

msv _(i−k) =ms _(i−k+1 v(i−k+1))−(ms _(i0) −me _(i−j0))/(j−1)

nsv _(i−k) =ns _(i−k+1 v(i−k+1))−(ns _(i0) −ne _(i−j0))/(j−1)

mev _(i−k) =ms _(i−k+1 v(i−k+1))

nev _(i−k) =ns _(i−k+1 v(i−k+1))

In the case where V−(i−j, 0) does not exist (step S507; N), i.e., in thecase where interpolation processing is carried out between vector at thecurrent processing time and point at the previous processing time of(i−j), initial points of respective vectors at the current processingtime and previous points are connected to divide distances therebetweenevery unit time required for passing through the distances to determineinterpolation values of respective vectors to add interpolation valuesof vectors (step S509) to return to the step S502. Interpolation valueV(i−k, v(i−k)) of vector is represented by the following formula in morepractical sense.

V(i−k,v(i−k))=(msp _(i−k) , nsp _(i−k) , mep _(i−k) , nep _(i−k))

In the above mentioned formula,

msp _(i−k) =ms _(i−k+1 v(i−k+1))−(ms _(i0) −m _(i−j0))/(j−1)

nsp _(i−k) =ns _(i−k+1 v(i−k+1))−(ns _(i0) −n _(i−j0))/(j−1)

mep _(i−k) =ms _(i−k+1 v(i−k+1))

nep _(i−k) =ns _(i−k+1 v(i−k+1))

If k=j holds (step S503; Y), interpolation processing of vector iscompleted to return to the step S103 (FIG. 8).

FIG. 14 shows interruption switch processing. In this interruptionswitch processing, interpolation processing of the interruptionprocessing is carried out. As this interpolation processing, there aretwo kinds of processing of processing which considers the interruptionswitch 17 to be in OFF state after scene change in the case where theinterruption switch 17 is turned OFF state within a predetermined timeafter scene change when ON state of the interruption switch 17 iscontinued from the time of scene change and processing which considersthe interruption switch 17 to be in ON state from the scene change timein the case where the interruption switch 17 is turned ON within apredetermined time after scene change when OFF state of the interruptionswitch 17 is continued from the scene change. In the interruption switchprocessing, the time i from the time when the scene has been changed andthe prescribed time TS are initially compared (step S601). When i issmaller than the prescribed time TS, n(i) is set to 1, i.e., N(i, 1) isset (step S602) to return to the step S106 (FIG. 8). It is to be notedthat when the interruption switch 17 is not pushed down and theinterpolation processing is not carried out, the interruption processingis not carried out while maintaining n(i)=1. In the case where theinterruption switch 17 is turned OFF within the prescribed time TS afterscene change when ON state of the interruption switch 17 is continuedfrom the scene change time by the processing of step S602, theinterruption switch 17 is assumed to be in OFF state after scene change.Thus, the interruption processing is not carried out from the time whenscene change has been conducted.

When i is equal to the prescribed time TS at step S601, n(i) is set to0, i.e., N(i, 0) is set (step S603) to carry out the interruptionprocessing to shift to interpolation processing. In this interpolationprocessing, the state of interruption processing at the previousprocessing time is initially confirmed to judge whether or not n(i−1) isequal to 0, i.e., N(i−1, 0) exists (step S604). In the case where N(i−1,0) exists (Y), the interruption processing is continued as it is toreturn to the step S106 (FIG. 8). In the case where N(i−1, 0) does notexist (N), j is initially set to 0 (step S605). Then, j+1 is caused tobe newly j (step S606) to judge whether or not N(i−j, 1) exists (stepS607). In the case where N(i−j, 1) exists (Y), current value is changedinto N(i−j, 0), i.e., the interruption processing is interpolated (stepS608). Then, whether i=j holds is judged (step S609). If i=j does nothold (N), the operation processing returns to the step S606. In the casewhere N(i−j, 1) does not exist (step S607; N) and in the case of i=j(step S609;Y), the operation processing returns to the step S106 (FIG.8). In the case where the interruption switch 17 is turned ON within theprescribed time TS after scene change when OFF state of the interruptionswitch 17 is continued from the time of scene change by such processing,the interruption switch 17 is assumed to be in ON state from the time ofscene change. Thus, the interruption processing is carried out from thetime of scene change.

At step S601, when i is greater than the prescribed time TS, N(i, 0) isset (step S610) to carry out interruption processing to return to thestep S106 (FIG. 8).

FIG. 15 to 19 show end processing. In this end processing, when scenechange signal from the switching precessing section 27 indicating changeof scene is inputted, in the case where there exists point or vectorinterpolated by the interpolation processing from end time of the sceneuntil the time point before predetermined end processing time TE, theinterpolation processing is carried out until change of the scene. Inthis example, the end processing time TE is set to 5 sec.

In this end processing, j is initially set to 0 (step S701) thereafterto allow j+1 to be newly j(step S702) thereafter to judge whether or noti−j is greater than TE (step S703). In the case where i−j is not greaterthan TE (N), whether or not N(i−j, 0) exists is judged (step S704). Inthe case where N(i−1, 0) does not exist (N), the operation processingreturns to the step S702. In the case where N(i−1, 0) exists (Y), theoperation processing proceeds to step S705. Thus, the interpolationprocessing is carried out with respect to j and values succeedingthereto. Also in the case where i−j is greater than TE (step S703; Y),the processing operation proceeds to the step S705.

At the step S705 and steps subsequent thereto, points interpolatedwithin the end processing time are retrieved. In more practical sense,variable k is set to 0 at the step S705 thereafter to allow k+1 to benewly k (step S706) thereafter to judge whether or not k=j holds (stepS707). In the case where k=j does not hold (N), variable q is caused tobe q=p(i−k−1) (step S708) to judge whether or not P(i−k−1, q), i.e.,interpolated point exists (step S709). If the interpolated pointP(i−k−1, q) does not exist (N), q−1 is caused to be newly q (step S710)to judge whether or not q is equal to 0 (step S711). If q is not 0 (N),the operation processing returns to the step S709. If q is equal to 0(Y), the operation processing returns to the step S706. If theinterpolated point P(i−k−1, q) exists (step S709; Y), the operationprocessing proceeds to the processing shown in FIG. 17. In the casewhere the interpolated point P(i−k−1, 0) cannot be found so that thereresults k=j (step S707; Y), the processing operation proceeds to theretrieval processing of the interpolated vector shown in FIG. 16.

In the processing shown in FIG. 16, the interpolated vector within theend processing time is retrieved. In more practical sense, variable k isset to 0 at step S712 thereafter to allow k+1 to be newly k (step S713)thereafter to judge whether or not k=j holds (step S714). In the casewhere k=j does not hold (N), variable q is caused to be q=v(i−k−1) (stepS715) to judge whether or not V(i−k−1, q), i.e., the interpolated vectorexists (step S716). If the interpolated vector V(i−k−1, q) does notexist (N), q−1 is caused to be newly q (step S717) to judge whether ornot q is equal to zero (step S718). If q is not equal to 0 (N), theoperation processing returns to the step S716. If q is equal to zero(Y), the operation processing returns to the step S713. If theinterpolated point V(i−k−1, q) exists (step S716; Y), the processingoperation proceeds to the processing shown in FIG. 18. In the case wherethe interpolated vector V(i−k−1, q) cannot be found out so that k=jholds (step S714; Y), whether or not encoding is completed is judged(step S719). In the case where encoding is completed (Y), positionprocessing at the position processing section 21 is completed. In thecase where encoding is not completed (N), the processing operationreturns to the step S101 (FIG. 8) for position processing in the nextscene to clear p(i), v(i), n(i) and i.

In the processing shown in FIG. 17, whether or not there existsnon-interpolated point P(i−k, 0) inputted for the next unit time ofpoint P(i−k−1, q) retrieved at the processing shown in FIG. 15 isinitially judged (step S801). If that point P(i−k, 0) exists (Y),whether or not distance PDN(i−k, 0, i−k−1, q) between that point and theretrieved point P(i−k−1, q) is smaller than ½ of PD_(ref) is judged(step S802). In this case, PDN is represented by the following formula.

 PDN(x,y,z,a)=(m _(xz) −m _(yz))²+(n _(xa) −n _(ya))²

In the case where PDN(i−k, 0, i−k−1, q) is smaller than ½ of PD_(ref)(step S802; Y), it is seen that the interpolated point P(i−k−1, q) ispoint interpolated by the interpolation processing usingnon-interpolated point P(i−k, 0). In this case, points of P(i−k, 0) areinterpolated until change of scene by the processing of the step S803and steps subsequent thereto. In more practical sense, variable r is setto 0 (step S803) thereafter to allow r+1 to be newly r (step S804) tojudge whether or not r=k holds (step S805). If r=k does not hold (N),p(i−r)+1 is caused to be newly p(i−r) (step S806), i.e., the number ofprocessing operations is incremented by 1 to allow interpolation valueP(i−r, p(i−r)) of point to be the same value (m_(i−k0), n_(i−k0)) as thepoint P(i−k, 0) to add this interpolation value (step S807) to return tothe step S804. By repeating the processing of the steps S804 to S807 sothat there results r=k, points of P(i−k, 0) are interpolated from thenext unit time of the non-interpolated point P(i−k, 0) until change ofscene. If there results r=k (step S805; Y), the operation processingreturns to the step S706 (FIG. 15).

In the case where non-interpolated point P(i−k, 0) inputted at the nextunit time of the retrieved point P(i−k−1, q) does not exists (step S801;N), i.e., in the case where value inputted at the next unit time is onlyvector or interpolation value, and in the case where PDN(i−k, 0, i−k−1,q) is not smaller than ½ of PD_(ref) (step S802; N), the operationprocessing returns to the step S706 (FIG. 15) without carrying out theinterpolation processing.

In the processing shown in FIG. 18, whether or not non-interpolatedpoint P(i−k, 0) inputted at the next unit time of vector V(i−k−1, q)retrieved by the processing shown in FIG. 16 exists is judged (stepS901). If that point P(i−k, 0) exists (Y), whether or not distanceVEDN(i−k, 0, i−k−1, q) between that point and end point of the retrievedvector V(i−k−1, q) is smaller than ½ of PD_(ref) is judged (step S902).In this case, VEDN is represented by the following formula.

VEDN(x,y,z,a)=(m _(xz) −me _(yz))²+(n _(xa) −ne _(ya))²

In the case where VEDN(i−k, 0, i−k−1, q) is smaller than ½ of PD_(ref)(step S902; Y), it is seen that the interpolated vector V(i−k−1, q) isvector interpolated by the interpolation processing usingnon-interpolated point P(i−k, 0). In this case, points of P(i−k, 0) areinterpolated until change of scene by the processing of the step S903and steps subsequent thereto. In more practical sense, variable r is setto 0 (step S903) thereafter to allow r+1 to be newly r (step S904) tojudge whether or not r=k holds (step S905). If r=k does not hold (N),p(i−r)+1 is caused to be newly p(i−r) (step S906), i.e., the number ofprocessing operations is incremented by 1 to allow interpolation value Pof point (i−r, p(i−r)) to be the same value (m_(i−k0), n_(i−k0)) as thepoint P(i−k, 0) to add this interpolation value (step S907) to return tothe step S904. By repeating the processing of the steps S904 to S907until there results r=k, points of P(i−k, 0) are interpolated from thenext unit time of non-interpolated point P(i−k, 0) until change ofscene. If there results r=k (step S905; Y), the operation processingreturns to the step S713 (FIG. 16).

In the case where non-interpolated point P(i−k, 0) inputted at the nextunit time of the retrieved vector V(i−k−1, q) does not exist (step S901;N), the operation processing proceeds to the processing shown in FIG.19. In addition, in the case where VEDN(i−k, 0, i−k−1, q) is not smallerthan ½ of PD_(ref) (step S902; N), the operation processing returns tothe step S713 (FIG. 16) without carrying out the interpolationprocessing.

In the processing shown in FIG. 19, whether or not there existsnon-interpolated vector V(i−k, 0) inputted at the next unit time ofvector V(i−k−1, q) retrieved at the processing shown in FIG. 16 isinitially judged (step S908). If that vector V(i−k, 0) exists (Y),whether or not distance VDN (i−k, 0, i−k−1, q) between initial point ofthat vector and end point of the retrieved vector V(i−k−1, q) is smallerthan ½ of PD_(ref) is judged (step S909). In this case, VDN isrepresented by the following formula.

 VDN(x,y,z,a)=(ms _(xz) −me _(yz))²+(ns _(xa) −ne _(ya))²

In the case where VDN(i−k, 0, i−k−1, q) is smaller than {fraction (1/2+L)} of PD_(ref) (step S909; Y), it is seen that the interpolated vectorV(i−k−1, q) is vector interpolated by the interpolation processing usingnon-interpolated vector V(i−k, 0). In this case, interpolation ofvectors is carried out until change of scene by the processing of thestep S910 and steps subsequent thereto. In more practical sense,variable r is set to k (step S910) thereafter to allow r−1 to be newly r(step S911) to judge whether or not r is equal to zero (step S912). If ris not zero (N), p(i−r)+1 is caused to be newly p(i−r) (step S913),i.e., the number of processing operations is incremented by 1 todetermine interpolation value of vector V (i−r, v(i−r)) to add thisinterpolation value of vector (step S914) to return to the step S911.Interpolation value of vector V(i−r, v(i−r)) is represented by thefollowing formula in more practical sense.

V(i−r,v(i−r))=(msk _(i−r) , nsk _(i−r) , mek _(i−r) , nek _(i−r))

In the above mentioned formula,

msk _(i−r) =ms _(i−r+1 v(i−r+1))−(ms _(i−k0) −m _(i−k0))

nsk _(i−r) =ns _(i−r+1 v(i−r+1))−(ns _(i−k0) −n _(i−k0))

mek _(i−r) =ms _(i−r+1 v(i−r+1))

nek _(i−r) =ns _(i−r+1 v(i−r+1))

By repeating the processing of the steps S911 to S914 so that thereresults r=0, interpolation of vectors is carried out from the next unittime of non-interpolated vector V(i−k, 0) until change of scene. Ifthere results r=o (step S912; Y), the operation processing returns tothe step S713 (FIG. 16).

In the case where non-interpolated vector V(i−k, 0) inputted at the nextunit time of the retrieved vector V(i−k−1, q) does not exist (step S908;N), i.e., in the case where value inputted at the next unit time is onlyinterpolation value, and in the case where VDN(i−k, p, i−k−1, q) is notsmaller than ½ of PD_(ref) (step S909; N), the operation processingreturns to the step S713 (FIG. 16) without carrying out theinterpolation processing.

As described above, values of points and values of vectors everyrespective unit times determined by the processing which has beendescribed with reference to FIGS. 8 to 19 are converted into pointvalues every frame, and point values every frame are caused to becentral position of the visual point position vicinity area. In thiscase, value of point at unit time serves as point value every frame asit is. On the other hand, in order to convert value of vector at unittime into point value every frame, it is sufficient to divide vector atunit time into vectors every frame to allow central point betweeninitial point and end point of vector every frame to be point valueevery frame.

While the position processing at the position processing section 21 hasbeen described as above, size processing at the size processing section23 is substantially similar to the position processing. Namely, in thesize processing, fixed value of size in the visual point positionvicinity area at unit time is defined in place of point in the positionprocessing, and change value of size in the visual point positionvicinity area at unit time is defined in place of vector in the positionprocessing. Further, also in the size processing, similarly to the caseof the position processing, interpolation processing of fixed value andchange value of size is carried out. In this example, in the sizeprocessing, the point greatly different from the position processing isthat since output signal of the size adjust lever 18 is delayed ascompared to the operation of the visual point, only values at the latterhalf portion within the unit time are used to determine fixed value andchange value of size. Values of sizes obtained by the size processingare determined so as to correspond to respective center positions (pointvalues every frame) of the visual point position vicinity areadetermined by the position processing. Accordingly, as informationrepresenting the visual point position vicinity area, three-dimensionalvalues (m, n, s) by point (m, n) and size (s) are obtained every frame.In this example, value s of size is set to 0 when the interruptionprocessing is being carried out. The system control section 30 generatescode quantity reduction control signal 35 on the basis of information(m, n, s) indicating visual point position vicinity area obtained inthis way to send it to the code quantity reduction section 13.

As explained above, in accordance with the picture compression encodingapparatus according to this embodiment, such an approach is employed todetect visual point position of operator to set visual point positionvicinity area on the basis of this visual point position and output ofsize adjust lever 18, thus making it possible to vary allocation of codequantity in dependency upon the area so that code quantity allocated tothe area except for the visual point position vicinity area is smallerthan code quantity allocated to the visual point position vicinity area.Accordingly, it is possible to compression-encode picture data on thereal time basis within a limited code quantity by simple operation, andto obtain picture (image) of high picture quality from a viewpoint ofvisual sense for user as far as possible at the time of decoding. Inaddition, only in the case where code quantity per predetermined time byoutput data of the compressing section 11 is above the prescribed value,processing to vary allocation of code quantity in dependency upon thearea is carried out. Accordingly, there is no possibility that whenthere is margin in the code quantity, the picture quality may beunnecessarily deteriorated. As a result, picture data can be encoded byeffectively utilizing limited code quantity, and there can be obtainedpicture (image) of high picture quality from a viewpoint of visual sensefor user as far as possible at the time of decoding.

Moreover, in accordance with the picture compression encoding apparatusaccording to this embodiment, since size of the visual point positionvicinity area can be changed, it is possible to set the area to whichlarge code quantity is allocated so that it has suitable size. Also fromthis point, picture data can be encoded by effectively utilizing limitedcode quantity, and there can be obtained picture (image) of high picturequality from a viewpoint of visual sense for user as far as possible atthe time of decoding.

Further, in accordance with the picture compression encoding apparatusaccording to this embodiment, since reduction of code quantity iscarried out stepwise from the visual point position vicinity area towardthe outside, it is possible to avoid that the boundary portion of thevisual point position vicinity area becomes conspicuous.

Further, in accordance with the picture compression encoding apparatusaccording to this embodiment, since interpolation processing of variouspoints and vectors are carried out, in the case where operatorrepeatedly carefully observes plural portions within picture in a mannersuch that the visual point is changed in succession, it is possible toset visual point position vicinity areas continuously in point of timerespectively in the vicinity of plural portions which have beencarefully observed, and it is possible to set visual point positionvicinity area also when the visual point position is not stable beforeand after change of scene. As a result, it can be prevented that visualpoint position vicinity areas are intermittently set. Thus, there can beobtained picture (image) of high picture quality from a viewpoint ofvisual sense for user at the time of decoding.

It is to be noted that this invention is not limited to theabove-described embodiments. For example, as the system of encoding inthe compressing section 11, other systems may be employed in addition tothe system in which DCT processing and bidirectional predictive encodingare used (combined). Further, as the method of reducing code quantity,in addition to the method of decreasing the number of bits allocated tocoefficients after undergone DCT processing, other methods, e.g.,reduction of pixels, etc. may be employed. In addition, variousmodifications may be made within the range which does not depart fromthe gist of this invention.

What is claimed is:
 1. A picture compression encoding apparatuscomprising: encoding means for compression-encoding input picture data;visual point position detecting means for detecting a visual pointposition within a picture that a viewer is currently observing bymonitoring the viewer's eyeball movements; area setting means forsetting a visual point position vicinity area centered on said visualpoint position detected by the visual point position detecting means;said visual point position vicinity area being an area smaller in sizethan said picture; and code quantity limiting means for limiting thequantity of code generated by said encoding means to a predeterminedquantity by adjusting the quantity of code allocated to the area of saidpicture outside of said visual point position vicinity area.
 2. Apicture compression encoding apparatus as set forth in claim 1, whereinthe code quantity limiting means decreases. stepwise code quantityallocated to the area except for the visual point position vicinity areatoward a direction away from the visual point position vicinity area. 3.A picture compression encoding apparatus as set forth in claim 1, whichfurther comprises selector means for selecting whether or not it iscarried out to vary allocation of code quantity in dependency upon areaby the code quantity limiting means.
 4. A picture compression encodingapparatus as set forth in claim 1, wherein the area setting means isadapted so that when visual point positions are intermittently detectedby the visual point position detecting means, visual point positionvicinity areas are continuously set between detection time points ofrespective visual point positions.
 5. A picture compression encodingapparatus as set forth in claim 1, wherein the area setting means isadapted so that the visual point position vicinity areas arecontinuously set for a time period between a time when visual pointposition is first detected by the visual point position detecting meanswithin picture unit consisting of plural frames or plural fields and atime when the picture unit is started.
 6. A picture compression encodingapparatus as set forth in claim 1, wherein the area setting means isadapted so that the visual point position vicinity areas arecontinuously set for a time period between a time when visual pointposition is detected last by the visual point position detecting meanswithin picture unit consisting of plural frames or plural fields and atime when the picture unit is completed.
 7. A picture compressionencoding apparatus comprising: encoding means for compression-encodinginput picture data; visual point position detecting means for detectinga visual point position within a picture that a viewer is currentlyobserving by monitoring the viewer's eyeball movements; area settingmeans for setting a visual point position vicinity area centered on saidvisual point position detected by the visual point position detectingmeans; said visual point position vicinity area being an area smaller insize than said picture; code quantity limiting means for limiting thequantity of code generated by said encoding means to a predeterminedquantity by adjusting the quantity of code allocated to the area of saidpicture outside of said visual point position vicinity area; and areaadjustable means for changing the size of the visual point positionvicinity area set by the area setting means.
 8. A picture compressionencoding apparatus as set forth in claim 7, wherein the code quantitylimiting means decreases stepwise code quantity allocated to an areaexcept for the visual point position vicinity area toward a directionaway from the visual point position vicinity area.
 9. A picturecompression encoding apparatus as set forth in claim 7, which comprisesselector means for selecting whether or not it is carried out to varyallocation of code quantity in dependency upon the visual point positionvicinity area by the code quantity limiting means.
 10. A picturecompression encoding apparatus as set forth in claim 7, wherein the areasetting means is adapted so that when the visual point positions areintermittently detected by the visual point position detecting means,visual point position vicinity areas are set continuously in point oftime for a time period between detection time points of respectivevisual point positions.
 11. A picture compression encoding apparatus asset forth in claim 7, wherein the area setting means is adapted so thatthe visual point position vicinity areas are continuously set for a timeperiod between a time when the visual point position is first detectedby the visual point position detecting means within picture unitconsisting of plural frames or plural fields and a time when the pixelunit is started.
 12. A picture compression encoding apparatus as setforth in claim 7, wherein the area setting means is adapted so that thevisual point position vicinity areas are continuously set for a timeperiod between a time point when visual point position is detected lastby the visual point position detecting means within picture unitconsisting of plural frames or plural fields and a time when the pictureunit is completed.
 13. A picture compression encoding method comprisingthe steps of: an encoding step of compression-encoding input picturedata; visual point position detecting step of detecting a visual pointposition within a picture that a viewer is currently observing bymonitoring the viewer's eyeball movements; an area setting step ofsetting a visual point position vicinity area centered on said visualpoint position detected by the visual point position detecting means;said visual point position vicinity area being an area smaller in sizethan said picture; and a code quantity limiting step of limiting thequantity of code generated at said encoding step to a predeterminedquantity by adjusting the quantity of code allocated to the area of saidpicture outside of said visual point position vicinity area.
 14. Apicture compression encoding method as set forth in claim 13, wherein,at the code quantity limiting step, a procedure is taken to decreasestepwise code quantity allocated to the area except for the visual pointposition vicinity area toward a direction away from the visual pointposition vicinity area.
 15. A picture compression encoding method as setforth in claim 13, which further comprises a selection step of selectingwhether or not it is carried out to vary allocation of code quantity independency upon area by the code quantity limiting step.
 16. A picturecompression encoding method as set forth in claim 13, wherein the areasetting step is such that when the visual point positions areintermittently detected by the visual point position detection step,visual point position vicinity areas are set continuously in point oftime for a time period between detection time points of the respectivevisual point positions.
 17. A picture compression encoding method as setforth in claim 13, wherein the area setting step is such that the visualpoint position vicinity areas are continuously set for a time periodbetween a time when the visual point position is first detected at thevisual point position detection step within picture unit consisting ofplural frames or plural fields and a time when the picture unit isstarted.
 18. A picture compression encoding method as set forth in claim13, wherein the area setting step is such that the visual point positionvicinity areas are continuously set for a time period between a timewhen the visual point position is detected last at the visual pointposition detection step within picture unit consisting of plural framesor plural fields and a time when the picture unit is completed.
 19. Apicture compression encoding method comprising the steps of: an encodingstep of compression-encoding input picture data; visual point positiondetecting step of detecting a visual point position within a picturethat a viewer is currently observing by monitoring the viewer's eyeballmovements; an area setting step of setting a visual point positionvicinity area centered on said visual point position detected by thevisual point position detecting means; said visual point positionvicinity area being an area smaller in size than said picture; a codequantity limiting step of limiting the quantity of code generated atsaid encoding step to a predetermined quantity by adjusting the quantityof code allocated to the area of said picture outside of said visualpoint position vicinity area; and an area adjustable step of varying thesize of the visual point position vicinity area set by the area settingstep.
 20. A picture compression encoding method as set forth in claim19, wherein, at the code quantity limiting step, a procedure is taken todecrease stepwise code quantity allocated to an area except for thevisual point position vicinity area toward a direction away from thevisual point position vicinity area.
 21. A picture compression encodingmethod as set forth in claim 19, which further comprises a selectionstep of selecting whether or not it is carried out to vary allocation ofcode quantity corresponding to area by the code quantity limiting step.22. A picture compression encoding method as set forth in claim 19,wherein the area setting step is such that when visual point positionsare intermittently detected by the visual point position detection step,the visual point position vicinity areas are set continuously in pointof time for a time period between detection time points of therespective visual point positions.
 23. A picture compression encodingmethod as set forth in claim 19, wherein the area setting step is suchthat the visual point position vicinity areas are continuously set for atime period between a time when the visual point position is firstdetected at the visual point position detection step within picture unitconsisting of plural frames or plural fields and a time when the pictureunit is started.
 24. A picture compression encoding method as set forthin claim 19, wherein the area setting step is such that the visual pointposition vicinity areas are continuously set for a time period between atime when the visual point position is first detected at the visualpoint position detection step within picture unit consisting of pluralframes or plural fields and a time when the picture unit is completed.